Speedtoys

Probly working on a crankcase pressurization system.

Denser air will pack the oil mist down. Pike's Peak Proven.

john gill

I am curious as to where or how the vacuum source is attached to the engine ?

Has anyone actually measured the sump pressure with a actual measurement device ?
or is this stated is that the plate data which would be different in any particular custom installation?

I ask as I have witnessed the heads covers fill with oil and if you attached the valve covers pcv pipes to a catch bucket (can whatever) they will fill with oil in no time at all at revs
If you remove the pipe from the neck and leave the pipe attached to the sump cover in the valley and the other end open, rev the engine to 5000 rpm it will shoot oil across the room .

I would assume that having a vacuum source attached to the engine a via a catch can would only encourage the catch can to accelerate the fill quickly and overflow .

How is all the pipe work attached , ?

ANyone who doubts what I have said above and lives near me in Brisbane , I am happy to perform the above experiment for free above using your car as the guinea pig , in real time in the Dyno.

Please be advised I am not being antagonistic , only asking legitimate questions and data that I have witnessed, as in my case I spend a lot of time in my car a full throttle and load , not tootling around the streets .

Alan

Well you seem pretty antagonistic to me as a starting point. Now assuming you really aren't and it's just the way you come off...

This is quite real - GTS cars are driving around like this because otherwise many of them just don't really work that well.

I have Greg's crank port oil baffle (because it is good), the top of the oil filler is sealed (no ports) except it feeds to the vacuum pump (where the air-pump used to be). Note: the rest of my config is not like Colin's. For me this feeds to a small high velocity centrifugal separator (spiral centrifugal flow and double flow inversions). This has a drain port (fluid) fed back to the pass cam cover and a vent port (vapor) fed back to the drivers cam cover (both of these have flow limiting restrictors - tuned) the primary fluid port has a sight glass chamber for flow monitoring. The output of the primary separator then feeds to a Provent 200 which only handles the net blowby flow, the plumbing size expands at the provent to reduce the velocity. The Provent drains to the sump via a check valve. The Provent output is fed in an effectively closed system manner (though not vacuum) back to the intake box - ahead of the filter using an expanded air-pump port on the passenger CAI tube/intake box top. The output is extremely clean, I did not plumb it to the airbox until I was quite convinced of that. But I did want a closed environmentally responsible system. I have also mentioned the Vacuum Limiting Valves these feed the rear cam cover ports (all 4 are plumbed & opened up) the VLV's are mounted inside the bottom of the air filter box (one at each end). They feed filtered fresh air into the cam covers whenever the vacuum level gets to ~7"Hg. This helps flush the crankcase a little which isn't otherwise done once the stock intake vacuum system system is plugged.

The cam covers vent ports only have inward flowing connections the 2 rear ones from VLV's, the 2 front ones from the primary separator pumped re-circulation loop. The throttle body feed & vac ports (the "Y") are just capped off. The filler neck ports are capped as is the intake vacuum line normally connected there.

Is it over complex - yes, was it difficult to plumb - you bet, did it take a long time - yes at least 2 years to complete with all the experiments along the way.

Did I measure vacuum - yes, continually for ~the first six months. Does it work - YES - it solves oil ingestion & excessive consumption, makes the car run cleaner (no pinging) power is up, driveability is way up, summer max oil temperatures are marginally down, wallet is emptier, knuckles were badly scraped, vocabulary was specially extended - smile was eventually restored.

I have way too much time and money into my car (you can't even imagine...) - so I wasn't going to take a risk with my engine by NOT solving this issue.

Greg continually harps on about how my car is about to die. Let's be clear I don't 'recommend' you do this - make your own choice. I did. I voted with my wallet just like Roger did. I genuinely did it because I was sick of the stock config crap - to me it was just broken. It was clear to me my engine was being slowly destroyed anyway - I just chose to do something about it.

I have no regrets - nothing Greg has said convinces me this is a bad idea for my car. As Greg feely admits he's never added a vacuum pump to a 928. And nobody is telling him he should.
I think it's clear there are many misconceptions about vacuum, to me in Arizona in the summertime a pressurized crank is a much worse thing...

Alan

john gill

ALan

What you have stated makes a lot of sense , certainly in the increase of power with the engine in a vacuum , you have progressed a few steps further than I dreamed as yes I tried to make a closed system , with the provent , but wasnt successful.

The stock system is a disaster , if the throttle snaps shut a high engine speed and in high gear , the oil that is drowning the neck of the oil filler is quickly sucked under vaccum and into the inlet manifold , I cant fathom why this was implemented in the first place .

However your description lost me , can you draw or have diagram of your
system ?

Thanks

UpFixenDerPorsche

John G.: there's a lot of info available re crankcase vacuum pumps.

This is a good start:

http://www.dragzine.com/tech-stories...up-horsepower/

Alan

John - I am an engineer - what I wrote is very precise. From what I wrote you can draw the system. I understand it might not be easily digestible - there is no easy way to do that - but it is all there.

I'm just tired of these threads degenerating into total pissing matches. To me this is a serious topic.

Greg has made his point that he thinks its a bad idea and that he would never do it. I am fine with that - I have no intention of convincing Greg to change his mind. However having made your point, there is no need to keep saying more of the same - Greg has no experience of doing this and others do.

So I think it's much more relevant to hear from those who have done it, what they have done, how and what worked and what didn't.

Lets put the caveats out there - don't do this thinking its guaranteed to work for you. If you don't have a GTS or go racing in an earlier car - this probably doesn't even apply to you. If you can't handle that there is major possible risk to go along with any reward - just don't do it. To do this you have to be willing to make choices and understand what you are going to do to balance risks - if you have no idea how to do this - it's probably best not to start down this path.


Otherwise we need to move on to a technical discussion without name calling or general (quite unjustified IMO) FUD thrown up at every turn.

Yes this is indeed still unproven over the long haul and it's only running on a small number of cars at this point - so clearly the jury is out on long term and broad effects. The systems installed vary so there is also not single config. But the way you get there is to talk it though and have those who are willing to take the risk chart the path for everyone else. Maybe the answer will turn out to be that it's a bad idea long term - far better we find that out based on those willing to try it. On the other hand maybe it turns out to be a fine solution for cars with ingestion issues and everyone affected has another realistic option.

Lets put the caveats on page 1 and in the title if we want. BUT ITS TIME TO JUST HAVE THE TECHNICAL DISCUSSION.

Greg you said:
Great - then lets act like that - because there are real learnings to be had here. But we have to be able to just talk about them - without having to wade though all the bull**** going on.

You have been clear on your concerns, and that you wouldn't do this. I think we are all OK with that. You have also been clear on your opinions on this and also things you have seen generally that you think are relevant to this. (and I for one have seriously thought about all of what you have said - I think I'd be stupid not to - I have way too much to lose...).

However to be fair you don't really have any observations (facts) about a vacuum pump system on a 928 because you never implemented one - right?

Lets move on to learning what we can from actual systems and actual results.

And those reading along shouldn't follow down this path without very serious consideration and understanding of the possible consequences.

Alan

Lizard928

The vacuum pump on my setup pulls vacuum from the factory filler neck.
It then exits the pump, goes through an air oil separator (AOS).
The AOS has an oil return on it which is routed to the 1/4 bank forward cam cover vent. The reduced pressure in the crankcase pulls the oil back in to the engine. This design also helps to limit the amount of vacuum that the system can produce inside the crankcase.

I have not measured the pressure in the crankcase with a stock breather setup on any variant. But I can tell you that on all engines without a vacuum pump (except maybe the new coyote engine), that there are pressure pulses as the pistons go up/down which reduce power, and cause a disturbance to the ring pack.

One can easily bring my system over it's limit and cause the AOS to overfill with oil, much like you stating you have seen the heads fill with oil.
I can also put an S4 on the dyno, and have the cam cover vents spit oil, or I can have them have not a drop. This is easily reproducible.
If the car is having any substantial level of detonation, the amount of oil that the engine ejects sky rockets.

There are many crankcase vacuum studies where the pushrod block guys found that at higher levels of vacuum the heads would fill with oil and starve the sump. This was caused by pulling vacuum on only 1 head, and the amount of air coming up the drain back holes prevented any oil from draining back down to the sump. The same happens on a 928, when you vent everything out the one valve cover, the level of airflow up and out the head is so high that the oil cannot return. When you get detonation, the rings will flutter, the volume of crankcase gasses increases, and makes the problem much worse.
So with the car that you are referring to that will puke oil out the cam covers, what is the CR, the camshafts, the octane run, AFR at top end, and the amount of ignition advance that you are running? In a hot climate like Brisbane, I would be adjusting the EZK and pulling a few degrees out of the WOT so as to give a slightly larger threshold.

What I did find is that on Joe's car, and on Rogers, regular driving on cooler days was never a problem. Not an ounce of oil ejected. Get some bad gas, or in Rogers case extreme heat both from the engine, and from heat soak. It would record less air going in due to the lighter density, and it would then stark to knock, and a little oil as Sean said would be ejected. Adjust the map slightly, problem disappeared.

john gill

ALl of my cars have the complete old engine management system removed, (road GT and the race ) the car I was referring to is the GT , the race car is about to be fired up , albeit having a dry sumped system.,it will also be able to perform as a sports sedan , with the evolution to having having independent throttle bodies . So everything I have learned from tracking the GT is being utilised in the race car version , to limit the engine eating the crank bearings . ( I do not use glycos anymore ,they are useless) CR is 11.4 to one , I use lambda as a reference, afr is not an accurate reference with highly oxygenated fuels , use only 98 octane as I have a Dynapack unit , I tune for best torque at high engine speeds , ie the numbers on the map all mean something . at high engine speeds I can get 30 degrees of advance , no detonation , how do I know this ,in the dyno everything is monitored , the engine has has microphones fitted to listen and monitor spurious engine noise ( for those that know they are incredibly noisy) timed to the firing strokes allowing it ot discern between noise and knocking detonation.
The stock ecu falls over in this area in the ST cars that I tuned it will be lucky to advance at high rpm more than 23 - 24 degress before the system thinks this is detonation, however due to the age of it is slow to process the information or the filtering circuit are not accurate enough . I understand that in the day this was probably good enough , but not for a modern race engine . Or for me as the replacement ecu allows me to code it my own logic to drive things like psd etc
I do not agree to pull timing out without knowing why you are are doing it , with the dynapack , you can hold the engine at any load and engine speed , whilst adding fuel and engine timing , building the best torque until this number stops , you know you have then arrived at the optimum at this engine speed and load, then move on to the next load point, etc etc . At the high engine load points the oil filler neck will be flooded with oil flung from the crank and pressure , to shoot oil across the room if you were to remove one of the hose ends , no one was more surprised then I when I first discovered this , in my race car this neck will be removed and a cover placed over it , you can now see why I am asking questions and considering the ramifcations of my intentions .

john gill

I had a look at that link JC , in my case the pump would fill with oil and be overwhelmed, I guess the solution is to somehow have the vacuum above a level the oil can get too , concur with the rest though.
Alans solution is interesting was too tired last night to get my head around his pipework though .

john gill

ALan

would it be possible to have a list of what your numbers on your photograph are or mean thanks ?

Tony

This place gets pretty catty sometimes.

Alan

Look here - lots more stuff too on other ideas:

https://rennlist.com/forums/showthre...eferrerid=6055 Starts around post #127 - but there is lots of other good stuff there before that.

Alan

Lizard928

I've done a number of systems with MegaSquirt and VEMS, so I fully understand what you are talking about. And I know about tuning it on each and every cell, I do the same but on a mustang dyno.
I have done it with both the stock computer and aftermarket computers.
And I can understand listing to the car with the microphones on the engine. Have you tried the old school method with a hose and set of ear muffs?

I used to think like you that the stock EZK was too sensitive and would retard on just junk noise. I have since changed my thought process to it not being strong enough. It does leave a tiny amount of power on the table, yes. But at what point is that extra couple of power worth it?
Todd Tremel is pushing almost 1,000rwhp out of his 928 with the TT. He does not have any oil being ejected out of his valve covers. He also sets his car up on the dyno logging and tuning every cylinder to be precise. He tunes it so that he has no detectable knocking present. I can tune a 928 with both the stock brain, and aftermarket brain and do run after run and slowly increase the ignition, and it is literally like an on/off switch once you go over that threshold and start to see knocking the amount of oil ejected is insane. So for a track car, I find that limit, and then pull a deg or 2 out to give myself a much larger safety limit and ensure there will be no issues on the track.

UpFixenDerPorsche

Alan, I do hope no hornets were harmed during the construction of that engine bay.

FredR

John,

An interesting post that aligns with my observations as I banged my head against a wall trying to find out what the problem was. The optimal timing cylinder to cylinder is all over the place [see Ken's recent work on his log] and this does not help. I found that my top end timing was limited to about 24 degrees when tuning with the EZ system and concluded [probably falsely] that there was something wrong with my motor. I put some of the problems down to my ineptitude but I now believe that what I did was correct relative to the "rules of the game" I was playing with. I noted that there was seemingly so much inconsistency/lack of repeatability in "knock events" this eventually led me to conclude that a lot of what it was reacting to was incorrectly filtered noise. The EZ system is very sensitive and works very well in the way it reacts but I do think quite a bit of what it is reacting to is noise. This leaves the tune rather conservative and explains why i see little to no oil in the Pro vent. It does not explain what I perceive to be high oil consumption.

I figured that excessive oil consumption could be linked to detonation given that on a stock motor [tuning/breathing etc] I found oil consumption was linked to revs and was told "they all do that". That they do is no longer in doubt- that they should do this is the issue. I figured that maybe even stock timing was overdone and maybe Porsche rely on the EZ to pull back a few degrees as and when needed to balance out the inter cylinder differences in timing.

I eventually concluded my problem was probably exaggerated by having a faster exhaust system requiring less advance due to reduced back pressure and of course hotter ambient air temps do not help either.

My first mistake on the breather system was to modify the system designed for my S4 motor to that on the GTS [I wanted the motor to look like a stock GTS]. For the breather system I was consistently advised to vent as much of the crankcase gases as possible and using my process engineering background scribbled out a design that might work. I then came across the John Kuhn baffle that pretty much replicated the principles I had in mind. This baffle works very well in that I see little signs of oil in my Pro-vent. Hopefully this is a good thing but ironically, may not be if it is restricting the gas flow out as it does its job. At the moment I do not know the answer to this one. If [as seems to be the case at the moment] the Pro vent is seemingly doing nothing why have it at all?

Initially I vented the crankcase filler to the Pro vent [1 inch connection] but that did not make much difference, I then vented the front cam cover crossover pipe into the Pro vent as well- that did not make much difference either. Then I vented the rear [1/4 bank] vent to the Pro Vent after opening up the restriction orifice and vented that into the mix- that seemed to attenuate the chronic oil consumption. Venting the cam towers alone does not make sense to me. If anything some pressure in there to push the oil down the drain channels would be a better bet.

I am still experimenting with the system bit by bit although whether anything will work to my aspiration remains to be seen. My motor will rev to the red line but it does not feel as thou it really wants to- this could be the cams of course.

Partial evacuation sounds as though it is a logical approach and the debate about what works and what does not is for sure "interesting". I guess time will tell whether it does anything untoward.

The minute we start making modifications indirectly we are saying "we know better than Porsche"- this may well hold true to some extent- with 30 years of experience of these motors the 928 community ought to be able to learn something about them. I listen to what others with much more experience advise and then make a value judgment about what I do next but if it goes wrong I would not blame those who were kind enough to try and advise me with good intent.

Rgds